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https://www.readbyqxmd.com/read/28304153/perpendicular-orientation-control-without-interfacial-treatment-of-raft-synthesized-high-%C3%AF-block-copolymer-thin-films-with-sub-10-nm-features-prepared-via-thermal-annealing
#1
Ryuichi Nakatani, Hiroki Takano, Alvin Chandra, Yasunari Yoshimura, Lei Wang, Yoshinori Suzuki, Yuki Tanaka, Rina Maeda, Naoko Kihara, Shinya Minegishi, Ken Miyagi, Yuusuke Kasahara, Hironobu Sato, Yuriko Seino, Tsukasa Azuma, Hideaki Yokoyama, Christopher K Ober, Teruaki Hayakawa
In this study, a series of perpendicular lamellae-forming poly(polyhedral oligomeric silsesquioxane methacrylate-block-2,2,2-trifluoroethyl methacrylate)s (PMAPOSS-b-PTFEMAs) was developed based on the bottom-up concept of creating a simple yet effective material by tailoring the chemical properties and molecular composition of the material. The use of silicon (Si)-containing hybrid high-χ block copolymers (BCPs) provides easy access to sub-10 nm feature sizes. However, as the surface free energies (SFEs) of Si-containing polymers are typically vastly lower than organic polymers, this tends to result in the selective segregation of the inorganic block onto the air interface and increased difficulty in controlling the BCP orientation in thin films...
March 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28295720/dual-phase-separation-in-a-semiconfined-system-monodispersed-heterogeneous-block-copolymer-membranes-for-cell-encoding-and-patterning
#2
Xiuyu Wang, Xueyan Feng, Guiping Ma, Di Zhang, Yahong Chai, Maofa Ge, Li Yao
Block copolymers (BCPs) have the capacity to self-assemble into a myriad of well-defined aggregate structures, offering great promise for the construction of drug delivery, photolithographic templates, and complex nanoscale assemblies. A uniqueness of these materials is their propensity to become kinetically frozen in non-equilibrium states, implying that the process of self-assembly can be utilized to remodel the resulting structures. Here, a new semiconfined system for processing the BCP self-assembly is constructed, in which an unusual dual-phase separation occurs, including nonsolvent-induced microphase separation and osmotically driven macrophase separation, ultimately yielding heterogeneous BCP membranes...
March 15, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28263052/gisaxs-analysis-of-the-in-depth-morphology-of-thick-ps-b-pmma-films
#3
Federico Ferrarese Lupi, Tommaso Jacopo Giammaria, Gabriele Seguini, Michele Laus, Pavo Dubček, Branko Pivac, Sigrid Bernstorff, Michele Perego
The morphological evolution of cylinder-forming poly(styrene)-b-poly(methyl methacrylate) block copolymer (BCP) thick films treated at high temperatures in the rapid thermal processing (RTP) machine was monitored by means of in-depth grazing-incidence small-angle X-ray scattering (GISAXS). The use of this nondisruptive technique allowed one to reveal the formation of buried layers composed of both parallel- and perpendicular-oriented cylinders as a function of the film thickness (24 ≤ h ≤ 840 nm) and annealing time (0 ≤ t ≤ 900 s)...
March 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28257204/linear-four-chalcogen-interactions-in-radical-cationic-and-dicationic-dimers-of-1-5-dichalcogena-canes-nature-of-the-interactions-elucidated-by-qtaim-dual-functional-analysis-with-qc-calculations
#4
Satoko Hayashi, Kengo Nagata, Shota Otsuki, Waro Nakanishi
The dynamic and static nature of extended hypervalent interactions of the (B)E···(A)E···(A)E···(B)E type are elucidated for four center-seven electron interactions (4c-7e) in the radical cationic dimers (1·(+)) and 4c-6e in the dicationic dimers (1(2+)) of 1,5-(dichalcogena)canes (2: (A)E(CH2CH2CH2)2(B)E: (A)E, (B)E = S, Se, Te, and O). The quantum theory of atoms-in-molecules dual functional analysis (QTAIM-DFA) is applied for the analysis. Total electron energy densities Hb(rc) are plotted versus Hb(rc) - Vb(rc)/2 [= (ℏ(2)/8m)∇(2)ρb(rc)] at bond critical points (BCPs) of the interactions, where Vb(rc) values show potential energy densities at BCPs...
March 15, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28257188/homochiral-evolution-in-self-assembled-chiral-polymers-and-block-copolymers
#5
Tao Wen, Hsiao-Fang Wang, Ming-Chia Li, Rong-Ming Ho
The significance of chirality transfer is not only involved in biological systems, such as the origin of homochiral structures in life but also in man-made chemicals and materials. How the chiral bias transfers from molecular level (molecular chirality) to helical chain (conformational chirality) and then to helical superstructure or phase (hierarchical chirality) from self-assembly is vital for the chemical and biological processes in nature, such as communication, replication, and enzyme catalysis. In this Account, we summarize the methodologies for the examination of homochiral evolution at different length scales based on our recent studies with respect to the self-assembly of chiral polymers and chiral block copolymers (BCPs*)...
March 3, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28225584/preferential-alignment-of-incommensurate-block-copolymer-dot-arrays-forming-moir%C3%A3-superstructures
#6
Cong Jin, Brian C Olsen, Erik J Luber, Jillian M Buriak
Block copolymer (BCP) self-assembly is of great interest as a cost-effective method for large-scale, high-resolution nanopattern fabrication. Directed self-assembly can induce long-range order and registration, reduce defect-density, and enable access to patterns of higher complexity. Here we demonstrate preferential orientation of two incommensurate BCP dot arrays. A bottom layer of hexagonal silica dots is prepared via typical self-assembly from a PS-b-PDMS block copolymer. Self-assembly of a second, or top, layer of a different a PS-b-PDMS block copolymer that forms a hexagonal dot pattern with different periodicity, results in a predictable Moiré superstructure...
February 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28195457/effect-of-entrapped-solvent-on-the-evolution-of-lateral-order-in-self-assembled-p-s-r-mma-ps-b-pmma-systems-with-different-thicknesses
#7
Tommaso Jacopo Giammaria, Federico Ferrarese Lupi, Gabriele Seguini, Katia Sparnacci, Diego Antonioli, Valentina Gianotti, Michele Laus, Michele Perego
Block copolymers (BCPs) are emerging as a cost-effective nanofabrication tool to complement conventional optical lithography because they self-assemble in highly ordered polymeric templates with well-defined sub-20-nm periodic features. In this context, cylinder-forming polystyrene-block-poly(methyl methacrylate) BCPs are revealed as an interesting material of choice because the orientation of the nanostructures with respect to the underlying substrate can be effectively controlled by a poly(styrene-random-methyl methacrylate) random copolymer (RCP) brush layer grafted to the substrate prior to BCP deposition...
February 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28165714/morphological-evolution-of-block-copolymer-particles-effect-of-solvent-evaporation-rate-on-particle-shape-and-morphology
#8
Jae Man Shin, YongJoo Kim, Hongseok Yun, Gi-Ra Yi, Bumjoon J Kim
Shape and morphology of polymeric particles are of great importance in controlling their optical properties or self-assembly into unusual superstructures. Confinement of block copolymers (BCPs) in evaporative emulsions affords particles with diverse structures, including prolate ellipsoids, onion-like spheres, oblate ellipsoids, and others. Herein, we report that the evaporation rate of solvent from emulsions encapsulating symmetric polystyrene-b-polybutadiene (PS-b-PB) determines the shape and internal nanostructure of micron-sized BCP particles...
February 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28159720/biphasic-calcium-phosphate-ceramics-for-bone-reconstruction-a-review-of-biological-response
#9
REVIEW
J M Bouler, P Pilet, O Gauthier, E Verron
Autologous bone graft is considered as the gold standard in bone reconstructive surgery. However, the quantity of bone available is limited and the harvesting procedure requires a second surgical site resulting in severe complications. Due to these limits, scientists and clinicians have considered alternatives to autologous bone graft. Calcium phosphates (CaPs) biomaterials including biphasic calcium phosphate (BCP) ceramics have proven efficacy in numerous clinical indications. Their specific physico-chemical properties (HA/TCP ratio, dual porosity and subsequent interconnected architecture) control (regulate/condition) the progressive resorption and the bone substitution process...
January 31, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28122854/early-to-mid-term-results-after-total-cavopulmonary-connection-performed-in-the-second-decade-of-life
#10
Alexandre Metras, Virginie Fouilloux, Mohammed Al-Yamani, Xavier Roques, Loic Macé, Jean-Benoît Thambo, Dominique Metras, Bernard Kreitmann, François Roubertie
OBJECTIVES: Total cavopulmonary connection (TCPC) performed in the second decade of life has rarely been studied. Thus, we investigated (bicentric study) early and late morbidity and mortality following completion of TCPC in these patients. METHODS: From January 1999 to June 2014, 63 patients (14.5 ± 2.9 years) underwent TCPC (extracardiac conduit). Palliation before completion was an isolated bidirectional cavopulmonary shunt (BCPS) in 3 patients or BCPS associated with additional pulmonary blood flow (APBF) that was either antegrade (Group 1) in 38 (63%) or retrograde (Group 2) in 22 (37%)...
January 25, 2017: Interactive Cardiovascular and Thoracic Surgery
https://www.readbyqxmd.com/read/28093463/bidirectional-cavopulmonary-anastomosis-with-additional-pulmonary-blood-flow-good-or-bad-pre-fontan-strategy
#11
Nataliya R Nichay, Yuriy N Gorbatykh, Igor A Kornilov, Ilya A Soynov, Sergey M Ivantsov, Artem V Gorbatykh, Dmitriy N Ponomarev, Alexander V Bogachev-Prokophiev, Alexander M Karaskov
OBJECTIVES: This study aimed to evaluate the influence of preserved additional pulmonary blood flow (APBF) on survival after bidirectional cavopulmonary shunt (BCPS) and completion of Fontan circulation. METHODS: From March 2003 and April 2015, 156 patients with a single ventricle underwent BCPS. After performing propensity score analysis (1:1) for the entire sample, 50 patients with APBF (APBF group) were matched with 50 patients without APBF (no-APBF group). RESULTS: Age (P = 0...
January 15, 2017: Interactive Cardiovascular and Thoracic Surgery
https://www.readbyqxmd.com/read/28068100/directed-self-assembly-of-polystyrene-b-poly-propylene-carbonate-on-chemical-patterns-via-thermal-annealing-for-next-generation-lithography
#12
Guan-Wen Yang, Guang-Peng Wu, Xuanxuan Chen, Shisheng Xiong, Christopher G Arges, Shengxiang Ji, Paul F Nealey, Xiao-Bing Lu, Donald J Darensbourg, Zhi-Kang Xu
Directed self-assembly (DSA) of block copolymers (BCPs) combines advantages of conventional photolithography and polymeric materials and shows competence in semiconductors and data storage applications. Driven by the more integrated, much smaller and higher performance of the electronics, however, the industry standard polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) in DSA strategy cannot meet the rapid development of lithography technology because its intrinsic limited Flory-Huggins interaction parameter (χ)...
January 27, 2017: Nano Letters
https://www.readbyqxmd.com/read/28067366/controlled-solvent-vapor-annealing-of-a-high-%C3%AF-block-copolymer-thin-film
#13
Ross Lundy, Shauna P Flynn, Cian Cummins, Susan M Kelleher, Maurice N Collins, Eric Dalton, Stephen Daniels, Michael A Morris, Ryan Enright
Molecular self-assembling block copolymers (BCPs) have shown promise as a next generation bottom-up lithography technology. However, a critical step in advancing this approach is the elimination of polymer dewetting due to bulk solvent nucleation and thermodynamically driven film rupture that can occur during the solvent vapor annealing process. We report on the pattern formation via phase segregation of spin coated diblock copolymer films through the investigation of annealing parameters in the limit of high solvent vapor saturation conditions that results in wafer-scale patterning without observing polymer dewetting defects...
January 9, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28051190/probe-into-the-influence-of-crosslinking-on-co2-permeation-of-membranes
#14
Jinghui Li, Zhuo Chen, Ahmad Umar, Yang Liu, Ying Shang, Xiaokai Zhang, Yao Wang
Crosslinking is an effective way to fabricate high-selective CO2 separation membranes because of its unique crosslinking framework. Thus, it is essentially significant to study the influence of crosslinking degree on the permeation selectivities of CO2. Herein, we report a successful and facile synthesis of a series of polyethylene oxide (PEO)-based diblock copolymers (BCP) incorporated with an unique UV-crosslinkable chalcone unit using Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT) process...
January 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/27997119/anisotropic-self-assembly-of-hairy-inorganic-nanoparticles
#15
Chenglin Yi, Shaoyi Zhang, Kyle Thomas Webb, Zhihong Nie
Current interest in functional assemblies of inorganic nanoparticles (NPs) stems from their collective properties and diverse applications ranging from nanomedicines to optically active metamaterials. Coating the surface of NPs with polymers allows for tailoring of the interactions between NPs to assemble them into hybrid nanocomposites with targeted architectures. This class of building blocks is termed "hairy" inorganic NPs (HINPs). Regiospecific attachment of polymers has been used to achieve directional interactions for HINP assembly...
January 17, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/27991788/surfactant-mediated-crystallization-driven-self-assembly-of-crystalline-ionic-complexed-block-copolymers-in-aqueous-solution
#16
Zaizai Tong, Runke Zhang, Pianpian Ma, Haian Xu, Hua Chen, Yanming Li, Weijiang Yu, Wangqian Zhuo, Guohua Jiang
A series of crystalline/ionic complexed block copolymers (BCPs) with various compositions have been prepared by sequential reactions. The BCPs with different hydrophilic fractions can self-assemble into various morphologies, such as spindlelike, rodlike, and spherical micelles with different crystallinity of the core. Bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) is added as a surfactant to induce the morphological transition of BCPs in aqueous media. The introduced AOT can be tightly bound to the cationic units, and a water-insoluble unit in the corona forms, leading to a reduced tethering density...
December 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/27987036/characterization-of-a-bacterioferritin-comigratory-protein-family-1-cys-peroxiredoxin-from-candidatus-liberibacter-asiaticus
#17
Anamika Singh, Narender Kumar, Prabhat P S Tomar, Sumit Bhose, Dilip Kumar Ghosh, Partha Roy, Ashwani K Sharma
To defend against the lethality of the reactive oxygen species (ROS), nature has armed microorganisms with a range of antioxidant proteins. These include peroxiredoxin (Prx) super family proteins which are ubiquitous cysteine-based non-heme peroxidases. The phytopathogenic bacterium Candidatus Liberibacter asiaticus (CLA), an etiological agent of citrus plants diseases, posses many genes for defense against oxidative stress. The bacterioferritin comigratory protein (BCP), a member of Prxs, is part of an oxidative stress defense system of CLA...
December 16, 2016: Protoplasma
https://www.readbyqxmd.com/read/27981945/nanoscale-silicon-substrate-patterns-from-self-assembly-of-cylinder-forming-poly-styrene-block-poly-dimethylsiloxane-block-copolymer-on-silane-functionalized-surfaces
#18
Dipu Borah, Cian Cummins, Sozaraj Rasappa, Scott M D Watson, Andrew R Pike, Benjamin R Horrocks, David A Fulton, Andrew Houlton, George Liontos, Konstantinos Ntetsikas, Apostolos Avgeropoulos, Michael A Morris
Poly(styrene)-block-poly(dimethylsiloxane) (PS-b-PDMS) is an excellent block copolymer (BCP) system for self-assembly and inorganic template fabrication because of its high Flory-Huggins parameter (χ ∼ 0.26) at room temperature in comparison to other BCPs, and high selective etch contrast between PS and PDMS block for nanopatterning. In this work, self-assembly in PS-b-PDMS BCP is achieved by combining hydroxyl-terminated poly(dimethylsiloxane) (PDMS-OH) brush surfaces with solvent vapor annealing. As an alternative to standard brush chemistry, we report a simple method based on the use of surfaces functionalized with silane-based self-assembled monolayers (SAMs)...
January 27, 2017: Nanotechnology
https://www.readbyqxmd.com/read/27960391/dual-functionality-fullerene-and-silver-nanoparticle-antimicrobial-composites-via-block-copolymer-templates
#19
Kyle J Moor, Chinedum O Osuji, Jae-Hong Kim
We present the facile prepartion of C70 and Ag nanoparticle (NP) loaded block copolymer (BCP) thin films, with C70 and Ag NPs working in tandem to provide virucidal and bactericidal activities, respectively. Polystyrene-block-poly-4-vinylpyridine (PS-P4VP) was used as a template, allowing C70 integration into PS domains and in situ formation of Ag NPs in P4VP domains, while providing control of the nanoscale spatial distribution of functionality as a function of BCP molecular weight (MW). C70 loaded PS-P4VP films were found to generate significant amounts of (1)O2 under visible light illumination with no apparent dependence on BCP MW...
December 14, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27862808/magneto-plasmonic-janus-vesicles-for-magnetic-field-enhanced-photoacoustic-and-magnetic-resonance-imaging-of-tumors
#20
Yijing Liu, Xiangyu Yang, Zhiqi Huang, Peng Huang, Yang Zhang, Lin Deng, Zhantong Wang, Zijian Zhou, Yi Liu, Heather Kalish, Niveen M Khachab, Xiaoyuan Chen, Zhihong Nie
Magneto-plasmonic Janus vesicles (JVs) integrated with gold nanoparticles (AuNPs) and magnetic NPs (MNPs) were prepared asymmetrically in the membrane for in vivo cancer imaging. The hybrid JVs were produced by coassembling a mixture of hydrophobic MNPs, free amphiphilic block copolymers (BCPs), and AuNPs tethered with amphiphilic BCPs. Depending on the size and content of NPs, the JVs acquired spherical or hemispherical shapes. Among them, hemispherical JVs containing 50 nm AuNPs and 15 nm MNPs showed a strong absorption in the near-infrared (NIR) window and enhanced the transverse relaxation (T2 ) contrast effect, as a result of the ordering and dense packing of AuNPs and MNPs in the membrane...
December 5, 2016: Angewandte Chemie
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